The distribution of YKL-40 in osteoarthritic and normal human articular cartilage

YKL-40, also called human cartilage glycoprotein-39, is a major secretory p rotein of human chondrocytes in cell culture. YKL-40 mRNA is expressed by c artilage from patients with rheumatoid arthritis, but is not detectable in normal human cartilage. The aim was to investigate the distribution of YKL- 40 in osteoarthritic (n=9) and macroscopically normal (n=5) human articular cartilage, collected from 12 preselected areas of the femoral head, to dis cover a potential role for YKL-40 in cartilage remodelling in osteoarthriti s. Immunohistochemical analysis showed that YKL-40 staining was found in ch ondrocytes of osteoarthritic cartilage mainly in the superficial and middle zone of the cartilage rather than the deep zone. There was a tendency for high number of YKL-40 positive chondrocytes in areas of the femoral head wi th a considerable biomechanical load. The number of chondrocytes with a pos itive staining for YKL-40 was in general low in normal cartilage. The prese nt findings, together with previous observations, suggests that YKL-40 may be of importance in cartilage remodeliing/degradation of osteoarthritic joi nts.